Ok, I generated a PGP key (with PGP 6.5.8) for email-Adress lets say karl@foo.com.
Everything is fine.

At next I want to use exact the same keypair which I generated above for another eMail address
e.g. karl@yahoo.com

How do I tell PGP to copy the existing key pair and replace the existing email-Adress by a new one?